1. Field of the Invention
The present invention relates generally to ammunition and explosives. It relates particularly to blasting caps, the performance of which is improved by the bonding of a flat, steel foil to the face of a blasting cap and perpendicular to its longitudinal axis.
2. Description of the Related Art
Ordinary blasting caps, which commonly include deep-drawn aluminum cups, produce fragment velocities of approximately 14,000 feet/second and very small, scattered impressions in witness blocks. Witness blocks are blocks of poly(methyl methacrylate) into which the face of a blasting cap is fired. The depth of penetration, as well as the pattern of the fragments are determined visually. Moreover, the donor initiation capability of such blasting caps (as measured by the maximum gap at which initiation can be achieved between a blasting cap and a standard HNS explosive acceptor) is in need of improvement, as a result of increased requirements in military and aerospace applications, and in such specialized industries as mining and exploration for oil.
Although U.S. Pat. No. 4,727,808 (Wang et al) discloses a steel-shelled explosive blasting cap and a cup made from soft steel sheet, and although U.S. Pat. No. 4,920,883 (Barker) discloses an exploding foil detonator, there is no disclosure in either of these references of the addition of a steel foil to an existing standard blasting cap, which is made of aluminum.